1. Field of the Invention
The invention relates generally to devices for protecting the ends of pipes. More particularly, the invention relates to devices for protecting the threads on the ends of pipes.
2. Background of the Technology
Pipes, such as pipes used for oil and gas drilling and production, are often produced in sections and are axially connected end-to-end. Typically, the connection involves the use of a male, externally threaded portion at one end of one pipe section that is threadingly engageable with a mating female, internally threaded portion at the end of an axially adjacent pipe section. The male, externally threaded end of a pipe is often referred to as the “pin end,” and the female, internally threaded end of a pipe is often referred to as the “box end.”
The ends of the pipe, including the threads, are subject to damage when not in actual use, such as from corrosion, impacts with other objects, or from being dropped, during transportation and storage. Such damage may render the pipe faulty or unusable, resulting in delay, hardship and increased expense. Devices known as “thread protectors” are commonly used to protect the ends of the pipe, and in particular, to protect the internal and external threads on the ends of the pipe from such damage. A “pin end” thread protector is connected to and protects the pin end of the pipe and associated external threads, and a “box end” thread protector is connected to and protects the box end of the pipe and associated internal threads. The thread protectors are designed to prevent damage to the respective pipe ends when the pipe impacts other objects, the ground or otherwise is subjected to external impacts. In addition, the thread protectors are designed to seal the ends of the pipe to reduce the potential for premature corrosion of the pipe and/or threads.
Pipes used for oil and gas drilling and production can vary in nominal diameter from two inches to over thirty inches. Further, many pipe manufacturing companies and exploration and production (E&P) companies have developed proprietary thread forms dictating thread geometry (e.g., square threads, trapezoidal threads), thread size (e.g., thread height), and thread pitch (e.g., threads per inch). In addition, the American Petroleum Institute (API) has several thread form standards. As a result, there are over 3000 different combinations of pipe diameters and thread forms.
To protect both the pin end and box end of a pipe section, conventional thread protectors typically come in two parts—a pin end thread protector that is disposed about the pin end of the pipe and includes internal threads that engage the external threads on the pin end; and a box end thread protector that is positioned in the box end of the pipe and includes external threads that engage the internal threads on the box end. The pin end thread protector is sized, configured, and designed such that its internal threads mate with the external threads of the pin end; and the box end thread protector is sized, configured, and designed such that its external threads mate with the internal threads of the box end. In other words, the internal threads of the pin end protector fit between the external threads of the pin end as the pin end protector is threaded onto the pin end, and the external threads of the box end protector fit between the internal threads of the box end as the box end protector is threaded onto the box end. For example, FIG. 1A illustrates a conventional pin end thread protector 10 disposed about a pin end 20 of a pipe section 50. Pin end thread protector 10 includes internal threads 11 that mate and engage with external threads 21 on pin end 20. Specifically, internal threads 11 are designed to have the same thread pitch as external threads 21, and to have a size and geometry that allows internal threads 11 to fit between and mate with external threads 21 of pin end 20. In FIG. 1B, a conventional box end thread protector 30 is shown disposed about a box end 40 of pipe section 50. Box end thread protector 30 includes external threads 31 that mate and engage with internal threads 41 on box end 30. Specifically, external threads 31 are designed to have the same thread pitch as internal threads 41, and to have a size and geometry that allows external threads 31 to fit between and mate with internal threads 41 of box end 40.
As previously described, there are over 3000 different combinations of pipe diameter and thread form. Accordingly, there are hundreds of different thread protectors, each sized, configured, and designed to mate with the particular combination of pipe diameter and pipe thread form. Significant time and expense are associated with the manufacture of such a large number of different thread protectors, as well as the storage of such a large number of different thread protectors.
Accordingly, there remains a need in the art for a single thread protector capable of protecting pipe ends having different thread forms. Such thread protectors would be particularly well received if they offered the potential to reduce manufacturing costs and inventory costs, and were configured for multiple re-uses.